#include "Murmurhash.h"

namespace base
{
	//-----------------------------------------------------------------------------
	// MurmurHash2, by Austin Appleby

	// Note - This code makes a few assumptions about how your machine behaves -

	// 1. We can read a 4-byte value from any address without crashing
	// 2. sizeof(int) == 4

	// And it has a few limitations -

	// 1. It will not work incrementally.
	// 2. It will not produce the same results on little-endian and big-endian
	//    machines.

	unsigned int MurmurHash2 ( const void * key, int len, unsigned int seed )
	{
		// 'm' and 'r' are mixing constants generated offline.
		// They're not really 'magic', they just happen to work well.

		const unsigned int m = 0x5bd1e995;
		const int r = 24;

		// Initialize the hash to a 'random' value

		unsigned int h = seed ^ len;

		// Mix 4 bytes at a time into the hash

		const unsigned char * data = (const unsigned char *)key;

		while(len >= 4)
		{
			unsigned int k = *(unsigned int *)data;

			k *= m; 
			k ^= k >> r; 
			k *= m; 

			h *= m; 
			h ^= k;

			data += 4;
			len -= 4;
		}

		// Handle the last few bytes of the input array

		switch(len)
		{
		case 3: h ^= data[2] << 16;
		case 2: h ^= data[1] << 8;
		case 1: h ^= data[0];
			h *= m;
		};

		// Do a few final mixes of the hash to ensure the last few
		// bytes are well-incorporated.

		h ^= h >> 13;
		h *= m;
		h ^= h >> 15;

		return h;
	} 

}